	<template>
		<view>
			<view class="scroll-view-container">
			  <!-- 左侧的滚动视图区域 -->
			  <scroll-view class="left-scroll-view" scroll-y :style="{height: wh + 'px'}" >
				<block v-for="(item, i) in cateList" :key="i">
				   <view :class="['left-scroll-view-item', i === active ? 'active' : '']" @click="activeChanged(i)">{{item.cat_name}}</view>
				</block>
			  </scroll-view>
			  <!-- 右侧的滚动视图区域 -->
			  <scroll-view class="right-scroll-view" scroll-y :style="{height: wh + 'px'}" :scroll-top="scrollTop">
			    <view class="cate-lv2" v-for="(item2, i2) in cateLevel2" :key="i2">
			      <view class="cate-lv2-title">/ {{item2.cat_name}} /</view>
			      <!-- 动态渲染三级分类的列表数据 -->
			      <view class="cate-lv3-list">
			        <!-- 三级分类 Item 项 -->
			        <view class="cate-lv3-item" v-for="(item3, i3) in item2.children" :key="i3" @click = "gotoGoodsList(item3)">
			          <!-- 图片 -->
			          <image :src="item3.cat_icon"></image>
			          <!-- 文本 -->
			          <text>{{item3.cat_name}}</text>
			        </view>
			      </view>
			    </view>
			  </scroll-view>
			</view>
		  </view>
	</template>

	<script>
		export default {
			data() {
			  return {
				// 窗口的可用高度 = 屏幕高度 - navigationBar高度 - tabBar 高度
				wh: 0,
				cateList: [],
				active:0,
				cateLevel2: [],
				scrollTop: 0,
			  };
			},
			onLoad() {
			  // 获取当前系统的信息
			  const sysInfo = uni.getSystemInfoSync()
			  // 为 wh 窗口可用高度动态赋值
			  this.wh = sysInfo.windowHeight
			  this.getCateList()
			},
			methods:{
				async getCateList(){
					let result = await uni.$http.get('/api/public/v1/categories')
					console.log(result)
					if(result.data.meta.status!==200) return uni.$showMsg()
					this.cateList = result.data.message
					this.cateLevel2 = result.data.message[0].children
				},
				activeChanged(i) {
				  this.active = i
				  // 为二级分类列表重新赋值
				  this.cateLevel2 = this.cateList[i].children
				  this.scrollTop = this.scrollTop === 0 ? 1 : 0
				},
				gotoGoodsList(item3) {
				  uni.navigateTo({
				    url: '/subpkg/goods_list/goods_list?cid=' + item3.cat_id
				  })
				}
			}
		  }
	</script>

	<style lang="scss">
		.scroll-view-container {
		  display: flex;
		
		  .left-scroll-view {
			width: 120px;
		
			.left-scroll-view-item {
			  line-height: 60px;
			  background-color: #f7f7f7;
			  text-align: center;
			  font-size: 12px;
		
			  // 激活项的样式
			  &.active {
				background-color: #ffffff;
				position: relative;
		
				// 渲染激活项左侧的红色指示边线
				&::before {
				  content: ' ';
				  display: block;
				  width: 3px;
				  height: 45px;
				  background-color: #c00000;
				  position: absolute;
				  left: 0;
				  top: 50%;
				  transform: translateY(-50%);
				}
			  }
			}
		  }
		  .cate-lv2-title {
		    font-size: 12px;
		    font-weight: bold;
		    text-align: center;
		    padding: 15px 0;
		  }
		  .cate-lv3-list {
		    display: flex;
		    flex-wrap: wrap;
		  
		    .cate-lv3-item {
		      width: 33.33%;
		      margin-bottom: 10px;
		      display: flex;
		      flex-direction: column;
		      align-items: center;
		  
		      image {
		        width: 60px;
		        height: 60px;
		      }
		  
		      text {
		        font-size: 12px;
		      }
		    }
		  }
		}
	</style>
